Incompatible changes from 1.2 to 2.0

GTK+ changed fairly substantially from version 1.2 to 2.0, much more
so than from 1.0 to 1.2. Subsequent updates (possibilities are 2.0 to
2.2, 2.2 to 2.4, then to 3.0) will almost certainly be much, much
smaller. Nonetheless, most programs written for 1.2 compile against
2.0 with few changes. The bulk of changes listed below are to obscure
features or very specialized features, and compatibility interfaces
exist whenever possible.

gtk_container_get_toplevels() was removed and replaced
with gtk_window_list_toplevels(), which has different
memory management on the return value
(gtk_window_list_toplevels() copies the
GList and also references each widget in the list,
so you have to g_list_free() the list after first
unref'ing each list member).

The gdk_time* functions have been removed. This
functionality has been unused since the main loop was moved into GLib
prior to 1.2.

The signature for GtkPrintFunc (used for
gtk_item_factory_dump_items())
has been changed to take a const gchar * instead of
gchar *, to match what we do for GLib, and other similar cases.

The detail arguments in the GtkStyleClass structure
are now const gchar *.

gtk_paned_set_gutter_size() has been removed, since the
small handle tab has been changed to include the entire area previously
occupied by the gutter.

gtk_paned_set_handle_size() has been removed, in favor of
a style property, since this is an option that only makes sense for themes
to adjust.

GDK no longer selects OwnerGrabButtonMask for button presses. This means
that the automatic grab that occurs when the user presses a button
will have owner_events = FALSE, so all events are
redirected to the grab window, even events that would normally go to
other windows of the window's owner.

GtkColorSelectionDialog has now been moved into it's
own set of files, gtkcolorseldialog.c and
gtkcolorseldialog.h.

gtk_widget_shape_combine_mask() now keeps a reference
count on the mask pixmap that is passed in.

The GtkPatternSpec has been moved to GLib as
GPatternSpec, the pattern
arguments to gtk_item_factory_dump_items() and
gtk_item_factory_dump_rc()
have thusly been changed to take a GPatternSpec
instead of a GtkPatternSpec.

Type system changes:

GTK_TYPE_OBJECT is not a fundamental type anymore. Type checks of the
style (GTK_FUNDAMENTAL_TYPE (some_type) == GTK_TYPE_OBJECT)
will not work anymore. As a replacement, (GTK_TYPE_IS_OBJECT (some_type))
can be used now.

The following types vanished: GTK_TYPE_ARGS, GTK_TYPE_CALLBACK,
GTK_TYPE_C_CALLBACK, GTK_TYPE_FOREIGN. The corresponding GtkArg
fields and field access macros are also gone.

The type macros GTK_TYPE_MAKE() and GTK_TYPE_SEQNO() vanished, use of
GTK_FUNDAMENTAL_TYPE() is discouraged. Instead, the corresponding GType
API should be used: G_TYPE_FUNDAMENTAL(), G_TYPE_DERIVE_ID(),
G_TYPE_BRANCH_SEQNO(). Note that the GLib type system doesn't build new
type ids based on a global incremental sequential number anymore, but
numbers new type ids sequentially per fundamental type branch.

The following type functions vanished/were replaced:

Old Function

Replacement

gtk_type_query()

being investigated

gtk_type_set_varargs_type()

-

gtk_type_get_varargs_type()

-

gtk_type_check_object_cast()

g_type_check_instance_cast()

gtk_type_check_class_cast()

g_type_check_class_cast()

gtk_type_describe_tree()

-

gtk_type_describe_heritage()

-

gtk_type_free()

-

gtk_type_children_types()

g_type_children()

gtk_type_set_chunk_alloc()

GTypeInfo.n_preallocs

gtk_type_register_enum()

g_enum_register_static()

gtk_type_register_flags()

g_flags_register_static()

gtk_type_parent_class()

g_type_parent()/g_type_class_peek_parent()

Use of g_type_class_ref()/g_type_class_unref() and g_type_class_peek()
is recommended over usage of gtk_type_class().
Use of g_type_register_static()/g_type_register_dynamic() is recommended
over usage of gtk_type_unique().

Object system changes:
GtkObject derives from GObject, so is not the basic object type anymore.
This imposes the following source incompatible changes:

GtkObject has no klass field anymore, an object's class can be retrieved
with the object's coresponding GTK_<OBJECT>_GET_CLASS (object)
macro.

GtkObjectClass has no type field anymore, a class's type can be retrived
with the GTK_CLASS_TYPE (class) macro.

GtkObjectClass does not introduce the finalize() and shutdown() methods
anymore. While shutdown() is intended for GTK+ internal use only, finalize()
is required by a variety of object implementations. GObjectClass.finalize
should be overriden here, e.g.:

The GtkObject::destroy signal can now be emitted multiple times on an object.
::destroy implementations should check that make sure that they take this
into account, by checking to make sure that resources are there before
freeing them. For example:

have to be moved into the ::destroy implementations. The reason for doing
this is that all object reference cycles should be broken at destruction
time.
Because the ::destroy signal can be emitted multiple times, it no longer
makes sense to check if a widget has been destroyed using the
GTK_OBJECT_DESTROYED() macro, and this macro has been
removed. If catching destruction is still needed, it can be done with a
signal connection to ::destroy.

Signal system changes:
The GTK+ 2.0 signal system merely proxies the GSignal
system now. For future usage, direct use of the
GSignal API is recommended,
this avoids significant performance hits where GtkArg
structures have to be converted into GValues. For
language bindings, GSignal+GClosure
provide a much more flexible and convenient mechanism to hook into signal
emissions or install class default handlers, so the old
GtkSignal API for language bindings is not
supported anymore.

Functions that got removed in the GTK+ signal API:
gtk_signal_n_emissions(),
gtk_signal_n_emissions_by_name(),
gtk_signal_set_funcs(),
gtk_signal_handler_pending_by_id(),
gtk_signal_add_emission_hook(),
gtk_signal_add_emission_hook_full(),
gtk_signal_remove_emission_hook(),
gtk_signal_query().
Also, the GtkCallbackMarshal argument to
gtk_signal_connect_full() is
not supported anymore.
For many of the removed functions, similar variants are available
in the g_signal_* namespace.
The GSignal system performs emissions in a
slightly different manner than the old GtkSignal
code. Signal handlers that are connected to signal "foo"
on object "bar" while "foo" is being emitted, will not be called anymore
during the emission they were connected within.

Inserting and deleting text in GtkEntry though
functions such as gtk_entry_insert_text() now leave
the cursor at its original position in the text instead of moving it to
the location of the insertion/deletion.

The label field of GtkFrame
widgets has been removed (as part of a change to allow arbitrary widgets
in the title position). The text can now be retrieved with the new function
gtk_frame_get_text().

The 'font' and 'font_set' declarations in RC files are now ignored. There
is a new 'font_name' field that holds the string form of a Pango font.

A number of types in GDK have become subclasses of
GObject. For the most part, this should not break
anyone's code. However, it's now possible/encouraged to use
g_object_ref()/g_object_unref() and
other GObject features with these GDK types. The
converted types are:
GdkWindow, GdkDrawable,
GdkPixmap, GdkImage,
GdkGC, GdkDragContext,
GdkColormap.

All drawables including pixmaps used to have a type tag, the
GdkWindowType enumeration, which included
GDK_WINDOW_PIXMAP.
GdkWindowType is now a property of
GdkWindowonly, and there is
no GDK_WINDOW_PIXMAP. You can use the
GDK_IS_PIXMAP() macro to see if you have a pixmap, if
you need to know that.

GtkStyle and GtkRcStyle are
now subclasses of GObject as well. This
requires fairly extensive changes to theme engines, but
shouldn't affect most other code.

xthickness and ythickness have moved from
GtkStyleClass to GtkStyle
(from class to instance). This gives themes a bit more flexibility
and is generally more of the Right Thing. You can trivially fix
your code with s/style->klass->xthickness/style->xthickness/g and
same for ythickness.

Some GtkStyledraw_* methods
have been removed (cross, oval, ramp)
and others have been added (expander, layout). This will require
changes to theme engines.

If you were using private GDK types, they have been rearranged
significantly. You shouldn't use private types. ;-)

The visual for a widget, and also the default visual is now derived
from the colormap for the widget and the default colormap.
gtk_widget_set_visual(),
gtk_widget_set_default_visual(),
gtk_widget_push_visual() and
gtk_widget_pop_visual() now do
nothing. Since the visual always had to match that of the colormap,
it is safe to simply delete all references to these functions.

A number of functions in GDK have been renamed for consistency and
clarity. #defines to provide backwards compatibility have been
included, but can be disabled by defining GDK_DISABLE_DEPRECATED.

(Note that g_object_ref() and
g_object_unref() may be used for all of the above ref
and unref functions.)
gtk_widget_popup() was removed, it was only usable
for GtkWindows, and there the same effect can be
achieved by gtk_window_move() and
gtk_widget_show().

gdk_pixmap_foreign_new() no longer calls
XFreePixmap() on the pixmap when the
GdkPixmap is finalized. This change corresponds
to the behavior of gdk_window_foreign_new(), and fixes
a lot of problems with code where the pixmap wasn't supposed to be freed.
If XFreePixmap() is needed, it can be done using the
destroy-notification facilities of g_object_set_data().

GtkProgress/GtkProgressBar
had serious problems in GTK+ 1.2.

Only 3 or 4 functions are really needed for 95% of progress interfaces;
GtkProgress/GtkProgressBar
had about 25 functions, and didn't even include these 3 or 4.

In activity mode, the API involves setting the adjustment
to any random value, just to have the side effect of
calling the progress bar update function - the adjustment
is totally ignored in activity mode.

You set the activity step as a pixel value, which means to
set the activity step you basically need to connect to
size_allocate.

There are ctree_set_expander_style()-functions, to
randomly change look-and-feel for no good reason.

The split between GtkProgress and
GtkProgressBar makes no sense to me whatsoever.

This was a big wart on GTK+ and made people waste lots of time,
both learning and using the interface.
So, we have added what we feel is the correct API, and marked all the
rest deprecated. However, the changes are 100% backward-compatible and
should break no existing code.
The following 5 functions are the new programming interface and you
should consider changing your code to use them:

The GtkNotebookPage structure has been removed from
the public header files;
this was never meant to be a public structure, and all functionality that
could be done by accessing the struct fields of this structure should be
accessible otherwise.

Negative values of the position parameter to
gtk_notebook_reorder_child() now cause the page to be appended, not
inserted at the beginning. (This gives consistency with
gtk_box_reorder_child(), gtk_menu_reorder_child().)

GtkMenuPositionFunc has a new parameter
push_in which controls how menus placed outside the
screen is handled. If this is set to TRUE and
part of the menu is outside the screen then GTK+ pushes it into the visible
area. Otherwise the menu is cut of at the end of the visible screen area.

Regardless of what happens to the size of the menu, the result is always
that the items are placed in the same place as if the menu was placed
outside the screen, using menu scrolling if necessary.

The "draw" signal and virtual method on GtkWidget
has been removed.
All drawing should now occur by invalidating a region of the widget
(call gdk_window_invalidate_rect() or
gtk_widget_queue_draw() for example to invalidate
a region). GTK+ merges all invalid regions, and sends expose events to
the widget in an idle handler for the invalid regions.
gtk_widget_draw() is deprecated but still works; it
adds the passed-in area to the invalid region and immediately sends
expose events for the current invalid region.
Most widgets will work fine if you just delete their "draw"
implementation, since they will already have working expose_event
implementations. The draw method was rarely called in practice
anyway.

The GdkExposeEvent has a new region
field. This can be used instead of the area field if you
want a more exact representation of the area to update.

Sending synthetic exposes using gtk_widget_event() is no
longer allowed. If you just need an expose call you should use
gdk_window_invalidate_rect() or
gdk_window_invalidate_region() instead. For the case
of container widgets that need to propagate expose events to
NO_WINDOW children you can either use
gtk_container_propagate_expose(), or chain to the
default container expose handler.

The draw_default and draw_focus methods/signals on
GtkWidget are gone; simply draw things in your
expose handler. gtk_widget_draw_focus() and
gtk_widget_draw_default() wrapper
functions are also gone; just queue a draw on the widget,
or the part affected by the focus/default anyway.
Also, GtkWidget now has default implementations for
focus_in_event and focus_out_event. These set/unset
GTK_HAS_FOCUS, and queue a draw. So if your focus in/out
handler just does that, you can delete it.

GtkText and GtkTree are
buggy and broken. We don't recommend using them, and changing old code to
avoid them is a good idea. The recommended alternatives are
GtkTextView and GtkTreeView.
The broken widgets are not declared in the headers by default; to use
them, define the symbol GTK_ENABLE_BROKEN during
compilation. In some future release, these widgets will be removed from GTK+.

GdkColorContext is gone; you probably weren't using
it anyway. Use GdkColormap and the
gdk_rgb_* functions instead.

GtkMenuBar now draws the GtkContainer::border_width
space outside the frame, not inside the frame.

In GTK+ 1.2, if an event handler returned TRUE it prevented
propagation of that event to parent widgets. That is, the
event signal would not be emitted on parent widgets. In
GTK+ 2.0, if an event handler returns TRUE, the current
signal emission on the current widget is immediately stopped. That is,
other callbacks connected to the signal will not be invoked.

gtk_toolbar_new() no longer has arguments. This function
was broken because the default GtkToolbarStyle (icons,
text, both) is now a user preference, which is overridden when you call
gtk_toolbar_set_style(). The constructor forced everyone
to override the preference, which was undesirable. So to port
your app, decide if you want to force the toolbar style
or conform to the user's global defaults; if you want to force
it, call gtk_toolbar_set_style().

The orientation arg was removed from gtk_toolbar_new()
as well, just because it wasn't very useful and we were breaking the function
anyway so had an opportunity to lose it. Call
gtk_toolbar_set_orientation() to set toolbar orientation.

GtkRange/GtkScrollbar/GtkScale were rewritten; this means that most
theme engines won't draw them properly, and any custom subclasses of
these widgets will need a rewrite (though if you could figure out
how to subclass the old version of GtkRange, you
have our respect). Also, GtkTroughType is gone.

Here are some notable changes:

stepper_size style property is the height for
vertical ranges, width for horizontal; the other dimension matches
the trough size.

Added the ability to do NeXT-style steppers (and several other styles
that don't make any sense).

Digits rounds the values a range will input to the given
number of decimals, but will not try to force adjustment
values set by other controllers. That is, we no longer
modify adjustment->value inside a
value_changed handler.

Added getters for GtkScale setters.

Middle-click begins a slider drag.

The GtkContainer::focus signal/virtual function and
gtk_container_focus() call were replaced by
GtkWidget::focus and gtk_widget_child_focus().
The semantics are the same, so you should be able to just
replace container_class->focus = mywidget_focus with
widget_class->focus = mywidget_focus and replace
gtk_container_focus() calls with
gtk_widget_child_focus() calls.

The purpose of this change was to allow non-containers to have
focusable elements.

gtk_rc_set_image_loader() and
gtk_rc_load_image() have been removed, now
that GTK+ includes decent image loading capabilities itself.

An extra GtkSettings argument has been added to
gtk_rc_find_pixmap_in_path(). This function is only
actually useful from a theme engine during parsing, at which point the
GtkSettings is provided.

The child argument facility in gtkcontainer.c has been
converted to a child property facility using
GParamSpec and other facilities
for GObject.

The set_child_arg() and get_child_arg()
virtual methods have been replaced with set_child_property()/get_child_property(), which
work similar to GObject->set_property/get_property.

Other removed GtkContainer functions with the replacements:

Old function

Replacement

gtk_container_add_child_arg_type

gtk_container_class_install_child_property

gtk_container_query_child_args

gtk_container_class_list_child_properties

gtk_container_child_getv

gtk_container_child_set_property

gtk_container_child_setv

gtk_container_child_get_property

gtk_container_add_with_args

gtk_container_add_with_properties

gtk_container_addv

gtk_container_add/gtk_container_child_set_property

gdk_image_get() (or rather its replacement,
gdk_drawable_get_image()) now handles errors properly
by returning NULL, previously it would crash. Also, a
window being offscreen is no longer considered an error; instead, the area
contains undefined contents for the offscreen areas. In most cases, code
using gdk_image_get() should really be ported to
gdk_pixbuf_get_from_drawable().

gtk_widget_set_usize() has been renamed to
gtk_widget_set_size_request(), however the old name
still exists unless you define GTK_DISABLE_DEPRECATED.

gtk_widget_set_uposition() is deprecated; use
gtk_window_move(),
gtk_fixed_put(), or gtk_layout_put()
instead.

gtk_window_set_policy() is deprecated. To get the effect of
"allow_shrink", call
gtk_widget_set_size_request (window, 0, 0). To get the
effect of "allow_grow", call
gtk_window_set_resizable (window, TRUE). You didn't want
the effect of "auto_shrink", it made no sense. But maybe if you were using
it you want to use gtk_window_resize (window, 1, 1) to
snap a window back to its minimum size (the 1, 1 will be rounded up to the
minimum window size).

The core GTK+ now takes care of handling mapping, unmapping and
realizing the child widgets of containers in
gtk_widget_set_parent(). In most cases, this allows
container implementations to be simplified by removing the code in
add() methods to map and realize children. However,
there are a couple of things to watch out for here:

If the parent is realized before the add() happens,
gtk_widget_set_parent_window() must be called before
gtk_widget_set_parent(), since
gtk_widget_set_parent() will realize the child.

If a container depended on its children not being mapped
unless it did so itself (for example, GtkNotebook
only mapped the current page), then the new function
gtk_widget_set_child_visible() must be called to keep
widgets that should not be mapped not mapped.

As part of this change, most containers also will no longer need custom
implementations of the map() and
unmap() virtual functions. The only cases where this
is necessary are:

For !NO_WINDOW widgets, if you create children of
widget->window
and don't map them in realize() then you must map them
in map(). [ In almost all cases, you can simply map the
windows in realize(). ]

For NO_WINDOW widgets, if you create windows in your
realize() method, you must map then in
map() and unmap them in unmap().

gtk_widget_set_default_style(),
gtk_widget_push_style(),
and gtk_widget_pop_style() have been removed, since they
did not work properly with themes and there were better
alternatives for modifying the appearance of widgets.
You should generally use gtk_widget_modify_*()
instead.

gtk_image_new() now takes no arguments and creates an
empty GtkImage widget. To create a
GtkImage widget from a
GdkImage (the least
common usage of GdkImage), use
gtk_image_new_from_image().

GTK_SELECTION_EXTENDED is now deprecated, and neither the
GtkList/GtkTree nor the
GtkCList/GtkCTree support
GTK_SELECTION_EXTENDED anymore. However, the old extended
behavior replaces MULTIPLE behavior.

The following variables are no longer exported from GDK. (Other variables
are also no longer exported; the following are the ones found used
externally in a large sample of GTK+ code.)

Variable

Replacement

gdk_null_window_warnings

None - did nothing in GTK+ 1.2

gdk_leader_window

None - private variable

gdk_screen

gdk_x11_get_default_screen ()

gdk_root_window

gdk_x11_get_default_root_xwindow ()

gdk_root_parent

gdk_get_default_root_window ()

gdk_error_code

gdk_error_trap_push ()/pop ()

gdk_error_warnings

gdk_error_trap_push ()/pop ()

gdk_display_name

gdk_get_display ()

gdk_wm_delete_window

gdk_atom_intern ("WM_DELETE_WINDOW", FALSE)

gdk_wm_take_focus

gdk_atom_intern ("WM_TAKE_FOCUS", FALSE)

gdk_wm_protocols

gdk_atom_intern ("WM_PROTOCOLS", FALSE)

The handling of colormaps and widgets has been changed:

The default colormap for widgets is now the GdkRGB
colormap, not the system default colormap. If you try to use resources
created for a widget (e.g., widget->style) with
a window using the system colormap, errors will result on some machines.

gtk_widget_push()/gtk_widget_pop_colormap()
only cause the colormap to be explicitly set on toplevel widgets, not on
all widgets. The colormap for other widgets (when not set using
gtk_widget_set_colormap()), is determined by finding
the nearest ancestor with a colormap set on it explicitly, or if that
fails, the default colormap.

The default selected day for GtkCalendar is now the
current day in the month, not the first day in the month. The current month
and year were already used.

GDK is no longer put into threaded mode automatically when
g_thread_init() has been called. In order to use the
global GDK thread mutex with gdk_threads_enter() and
gdk_threads_leave(), you must call
gdk_threads_init() explicitly.
If you aren't using GDK and GTK+ functions from multiple threads,
there is no reason to call gdk_threads_init().

The GtkPreviewInfo struct has had its visual and
colormap fields removed. Also, gtk_preview_get_cmap()
and gtk_preview_get_visual() are deprecated, as
GdkRGB works on any colormap and visual. You no
longer need to
gtk_widget_push_cmap (gtk_preview_get_cmap ()) in
your code.

The GtkBox, GtkTable, and
GtkAlignment widgets now call
gtk_widget_set_redraw_on_allocate (widget, FALSE); on
themselves. If you want to actually draw contents in a widget derived from
one of these widgets, you'll probably want to change this
in your init() function.

A number of widgets are now NO_WINDOW widgets (most
importantly GtkButton, but also
GtkRange and GtkNotebook)
This has a couple of effects:

If you are deriving from one of these widgets, you need to
adapt your code appropriately -- for instance, drawing coordinates
start from widget->allocation.x, widget->allocation.y.

If you are embedding one of these widgets in a custom widget,
you must make sure you call gtk_container_propagate_expose()
correctly, as you must for any NO_WINDOW widgets.

GtkFixed is a little special; it is now created by
default as a NO_WINDOW widget, but if you do

gtk_fixed_set_has_window (fixed, TRUE);

after creating a fixed widget, it will create a window and
handle it properly.

GtkLayout no longer has the xoffset,
yoffset fields, which used to store the difference between
world and window coordinates for layout->bin_window.
These coordinate systems are now always the same.

gtk_paint_focus(), gtk_draw_focus()
and GtkStyle::draw_focus()
have been changed a bit:

A GtkStateType argument has been added to gtk_paint_focus().

The default implementation of the GtkStyle::draw_focus()
virtual function now draws a focus rectangle whose width is
determined by the GtkWidget::focus-width style property.

The rectangle passed in is the bounding box, instead of
the rectangle used in the gdk_draw_rectangle() call,
so it is no longer necessary to subtract 1 from the width and height.